Chapter 41: Inoue-Balloon Mitral Valvuloplasty

INTRODUCTION

The introduction of percutaneous balloon mitral valvuloplasty (BMV) by Inoue et al¹ in 1982 has opened a new dimension in the treatment of patients with mitral stenosis. The body of data accrued to date has clearly established this invasive, nonsurgical procedure as the treatment of choice in symptomatic patients with moderate to severe mitral stenosis (mitral valve area <1.5 cm²) and favorable valve morphology (noncalcified, pliable valve with minimal subvalvular disease and no or mild mitral regurgitation).^2-5 The presence of either severe (grade ≥3) angiographic mitral regurgitation or left atrial thrombus is considered to be a contraindication for BMV. However, several controversial issues in the use of this procedure exist, because the selection of patients for BMV in clinical practice continues to be a complex decision involving consideration of multiple variables, including clinical profile, operator skill, valve morphology, and severity of associated mitral regurgitation.

Among the multiple variables, valve morphology and severity of associated mitral regurgitation have, to a large extent, remained the principal determinants in patient selection. In patients with favorable valve morphology (pliable, noncalcified valve with minimal subvalvular disease) and no or mild mitral regurgitation, BMV predictably yields excellent results and a low risk of resultant severe mitral regurgitation. With successful balloon valve enlargement, there is generally a 2-fold increase in the mitral valve area and an associated dramatic fall in transmitral valve gradient, left atrial pressure, and pulmonary artery pressure.^2-5 These hemodynamic benefits are mirrored in clinical improvements in the patients’ symptoms and exercise tolerance.

This is not entirely surprising, considering the fact that BMV enlarges the stenosed mitral valve in the same manner as that afforded by surgical commissurotomy—namely that of commissural split. Several randomized trials^6-11 comparing BMV and closed and/or open surgical commissurotomy in patients with favorable valve morphology have demonstrated that BMV is as efficacious, if not more so, than surgical mitral commissurotomy in acutely relieving the obstructed valve and achieving favorable clinical outcome. The long-term results of BMV are excellent, especially when the acute results are optimal and valve morphology is good. Long-term data in BMV have also indicated that after optimal mitral valve dilation, the restenosis rate is low and the acute symptomatic benefits are sustained.^12-16 When restenosis is defined as mitral valve area less than 1.5 cm², the restenosis rate in patients with favorable valve morphology at 7-year follow-up in the randomized trial by Farhat et al¹¹ was 6.6% in patients who underwent BMV; this rate was similar in those who underwent open surgical commissurotomy and was far superior to the restenosis rate of 37% observed after closed surgical commissurotomy. Hernandez and associates¹⁶ found that survival free of major events (cardiac death, mitral surgery, repeat BMV, or functional impairment) was 69% at 7 years, ranging from 88% to 40% in different subgroups of patients. Mitral area loss, although mild (0.13 ± 0.21 cm²), ...